I've had 2 AKG K702 and their bass was very good, tight, clean, layered and extended. Among the best in its class.
Superior to the woolier and more monotonous bass on my HD600 and HD650, also clearer and more delineated than the bass on my DT880.
AKG K702's bass is far from boosted though, so it only pairs very well with top class audiophile recordings intended to be played on very flat gear, just like HD800/HD800S.
They won't rock the house with average recordings, that's granted. Play a perfectly recorded acoustic bass or the lower registers on a nice piano and the bass will perform very well.
Fast and clean unlike most other dynamic headphones in its price range.
I would really understand if you say K702's bass wasn't present enough for your preferences and recordings, but I can't agree about it being really bad.
There's still a chance you're K702 was off somehow, but it's not very likely I guess.
Please expand on why you've found the bass on your K702 to be really bad, and what recordings you've used to judge it.
The gear used might help too.